IBM are still actively developing PPC architecture, ALL three games consoles out there use a PPC in some form. We have Xenon, CELL and Broadway. OK Broadway is rubbish and pre G4 speeds but that still leaves two completed CPUs that are PPC compatible. I doubt very much Microsoft would change from PPC back to Intel either, so expect to see a revised Xenon II within a few years (not the rubbish 16 colour s-l-o-w game from the bitmap bros!!).
IBM/LSI, AMCC and Freescale have all announced new chips recently, it isn't dead by any means. PPC isn't targeting the desktop anymore but they are getting faster. There is an upgrade path but with Amiga volumes don't expect them to be cheap.
They wont be competitive with most modern PCs but I don't think they'll be quite so bad as some are suggesting. The expect X1000 is going to be a lot better than a 2003 vintage PC. I don't know how the core will compare but it has a dual channel on-die memory system - similar to that found in today's mainstream PCs.
Unfortunately SPEC has not had a good reputation for a long time and it's got a lot worse recently. The only way to find out real performance is to try it and see.
